IPLookup
IPv4 vs IPv6: What's the Difference?
IPv4 and IPv6 are two versions of the Internet Protocol that define how devices communicate on the internet. While IPv4 is still the most widely used, IPv6 is the future as the world runs out of available IPv4 addresses.
Quick Comparison
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address size | 32-bit | 128-bit |
| Address format | Numeric dotted-decimal (e.g., 192.168.1.1) | Hexadecimal colon-separated (e.g., 2001:db8::1) |
| Total addresses | ~4.3 billion | ~340 undecillion (2^128) |
| Security | Optional IPSec | Built-in IPSec support |
| NAT (Network Address Translation) | Required for most networks | Not needed (enough addresses) |
| Configuration | Manual or DHCP | Stateless auto-configuration (SLAAC) |
| Packet fragmentation | By routers | By sender only |
What Is IPv4?
IPv4 (Internet Protocol version 4) was introduced in 1981 and is the first widely adopted version of the Internet Protocol. It uses a 32-bit address space, allowing for approximately 4.3 billion unique addresses. An IPv4 address is written as four decimal numbers separated by dots, like 192.168.1.1.
When the internet was first designed, 4.3 billion addresses seemed more than enough. But with the explosion of internet-connected devices — smartphones, laptops, smart TVs, IoT devices — the world has run out of available IPv4 addresses. This is the primary reason IPv6 was created.
What Is IPv6?
IPv6 (Internet Protocol version 6) was introduced in 1998 to solve the IPv4 address exhaustion problem. It uses a 128-bit address space, providing approximately 340 undecillion addresses — that's 340 trillion trillion trillion. An IPv6 address is written as eight groups of four hexadecimal characters separated by colons, like 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
IPv6 also includes improvements in security (built-in IPSec), simpler header format for faster processing, and stateless address auto-configuration (SLAAC) that allows devices to generate their own IP addresses without a DHCP server.
Why Is the Internet Migrating to IPv6?
The primary reason is address exhaustion. The IANA (Internet Assigned Numbers Authority) allocated the last remaining IPv4 address blocks in 2011. Since then, ISPs and organizations have been unable to get new IPv4 addresses without buying them on a secondary market at high prices.
IPv6 adoption has grown steadily. Major ISPs, cloud providers (AWS, Google Cloud, Azure), and content delivery networks (Cloudflare, Akamai) all support IPv6. Google reports that over 40% of their users access their services over IPv6.
Does IPv6 Affect My Privacy?
IPv6 can have privacy implications. Unlike IPv4, which typically uses NAT to hide internal devices, IPv6 gives every device a globally routable address. This means each device could potentially be tracked across the internet.
To address this, IPv6 includes privacy extensions that generate temporary, randomized addresses that change over time, making it harder to track devices.
How to Check If You're Using IPv4 or IPv6
Visit our IP lookup page. If your IP address follows the dotted-decimal format (e.g., 203.0.113.1), you're using IPv4. If it contains colons and hexadecimal characters (e.g., 2001:db8::1), you're using IPv6. Most users today still use IPv4.